Foldable intraocular lens and method of making

ABSTRACT

A foldable intraocular lens for providing vision contains an optic body that includes an optical zone and a peripheral zone entirely surrounding the optical zone. The optic body has an anterior face, a substantially opposing posterior face, an optic edge, and an optical axis. The anterior face comprises a central face, a peripheral face, and a recessed annular face therebetween that is disposed posterior to the peripheral face. The intraocular lens further comprises at least one haptic that is integrally formed with the peripheral zone. The haptic comprises a distal posterior face, a proximal posterior face, and a step edge disposed at a boundary therebetween. The haptic further comprises a side edge disposed between the optic edge and the step edge. The proximal posterior face and the posterior face of the optic body form a continuous surface. An edge corner is formed by the intersection of the continuous surface with the optic edge, the side edge, and the step edge.

RELATED APPLICATION

This application is a continuation of, and claims priority to, U.S.patent application Ser. No. 13/776,369, filed on Feb. 25, 2013, now U.S.Pat. No. 9,259,308, which is a continuation application of, and claimspriority to, U.S. patent application Ser. No. 12/567,425, filed on Sep.25, 2009, now U.S. Pat. No. 8,382,832, which is a continuationapplication of, and claims priority to, U.S. patent application Ser. No.11/010,003, filed on Dec. 9, 2004, now U.S. Pat. No. 7,621,949, whichclaims priority to U.S. Provisional Application No. 60/528,273, filed onDec. 9, 2003, all of which are hereby incorporated by reference in theirentirety for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to a foldable intraocular lens and morespecifically to a foldable intraocular lens having at least oneintegrally formed haptic with a step edge configured to reduce posteriorcapsule opacification (PCO), stabilize the intraocular lens, and/orreduce the volume of the intraocular lens.

Description of the Related Art

Foldable ophthalmic lenses, such as intraocular lenses (IOLs), are usedto replace the natural lens of an eye, for instance, when the naturallens is removed due to cataracts. Three-piece IOLs typically comprise anoptic made of a soft, foldable material into which stiffer fixationmembers or haptics are staked to provide centering and stabilization ofthe lens. One-piece IOLs are also available in which the haptics orfixation members are integrally formed with the optic from the samefoldable material as the optic.

One problem found with IOLs implanted in the capsular bag is that ofposterior capsular opacification (PCO), a condition in which remnantequatorial lens epithelial cells (LECs) migrate between the posteriorcapsule surface and the posterior surface of the IOL. The incidence ofPCO may be reduced by providing a continuous, sharp posterior corneraround the entire posterior surface of the optic to impede cellmigration into the lens area (e.g., U.S. Pat. Nos. 6,162,249 and6,468,306, which are herein incorporated by reference). However, in thecase of one-piece IOLs, haptic materials are generally soft, resultingin relatively bulky haptics that are thought to compromise the blockageof cell growth into the lens area. The haptics are especially bulkyproximal to the lens, where greater rigidity is used to support thehaptics and to help prevent the distal portions of haptics from stickingto the optic after insertion into the eye. Therefore, despite the use ofsharp, square optic edges, the bulky haptics used in one-piece IOLs canlead to an increased incidence of PCO, as compared to similarthree-piece IOLs (Miho Sugita, et al., American Journal ofOphthalmology, February 2004, vol. 137, no. 2, pp 377-379).

One reason for the increased prevalence of PCO in one-piece IOLs isthought to be that the relatively bulky haptics present an obstacle inattachment of the anterior capsule with the posterior capsule. This“shrink-wrap” effect may be advantageously used to pull the posteriorcapsule surface tight against the sharp posterior corner of the IOL.Ideally, the best corner seal should occur when there are no hapticspresent at all. The bulky haptics of a one-piece IOL move further fromthis ideal than the smaller haptic generally used in three-piece IOLs,thus providing a possible explanation of the higher incidence of PCO forone-piece IOLs.

In certain designs, a step edge is also formed on the optic in thevicinity of the haptics, providing in a continuous, 360 degree circularedge seal that surrounds the center of the lens and the posteriorcapsule. While this 360 degree edge seal configuration is relativelystraightforward to implement in three-piece IOLs, it is more difficultfor one-piece IOLs, since construction of an effective step edge in thearea of the haptics can compromise other IOL design parameters. Forinstance, if the optic edge is made relatively thin, in order to reduceoverall IOL volume, the haptic may be too thin to provide a desiredamount of stiffness if a step edge is incorporated. Conversely, if theoptic edge is made relatively thick, in order to provide a suitableattachment area for a thicker, stiffer haptic and to allow room for asuitable step edge, then the overall IOL volume may be too large,potentially leading to undesirably large incisions in the eye.

One way of helping to decrease the total IOL volume is disclosed in U.S.Pat. No. 5,476,513 to Brady et al., which is herein incorporated byreference. The '513 patent teaches an IOL having an optical zonesurrounded by a peripheral zone, wherein the peripheral zone is thickerthan the adjacent periphery of optical zone. Using this construction,the inlaid optical zone may be made thinner than it might otherwise bein an equivalent IOL not having a thicker peripheral zone. One potentialproblem with such an inlaid optical zone is that relatively sharpcorners can contribute to undesired optical effects such as halos orvisual poor contrast (e.g., FIG. 3A of the '513 patent). Such a designapproach also does not address the problem of PCO.

Therefore, one-piece IOLs are needed that are simultaneously resistantto PCO, have an overall volume that is sufficiently small for deliverythrough a relatively small ocular incision, and produce a low level ofscattered light.

SUMMARY OF THE INVENTION

The present invention is directed to an intraocular lens that may beplaced in the posterior chamber of a mammalian eye, comprising anoptical zone and an integrally formed haptic with a step edge that iscontiguous around the entire posterior edge of the optical zone. Asdiscussed in greater detail below herein, the intraocular lens providesboth a high resistance to the migration of LECs under the posterioroptic surface and an overall volume that is sufficiently small fordelivery through a relatively small ocular incision.

One aspect of the invention involves a foldable intraocular lenscontaining an optic body that includes an optical zone and a peripheralzone entirely surrounding the optical zone. The optic body has ananterior face, a substantially opposing posterior face, an optic edge,and an optical axis. The anterior face comprises a central face, aperipheral face, and a recessed annular face therebetween that isdisposed posterior to the peripheral face. The intraocular lens furthercomprises at least one haptic that is integrally formed with theperipheral zone. The haptic comprises a distal posterior face, aproximal posterior face, and a step edge disposed at a boundarytherebetween. The haptic further comprises a side edge disposed betweenthe optic edge and the step edge. The proximal posterior face and theposterior face of the optic body form a continuous surface. An edgecorner is formed by the intersection of the continuous surface with theoptic edge, the side edge, and the step edge. The distal posterior facemay be substantially perpendicular to the optical axis or disposed at anangle relative to a plane perpendicular to the optical axis. In thelater case, the angle is preferably in the range of about 2 degrees toabout 12 degrees or greater.

The haptic may be characterized by a haptic thickness that is equal to adistance along the optical axis that is between the distal posteriorface and a substantially opposing haptic anterior face. The hapticthickness is preferably greater than or approximately equal to an opticedge thickness along the optical axis. In one embodiment, at least oneof the haptic thickness or the optic edge thickness along the opticalaxis is in the range of at least about 0.4 mm or less to about 0.5 mm ormore. At least a portion of step edge may be configured to form asubstantially straight line and/or an arcuate shape. In certainembodiments, the step edge tapers radially, while in other embodimentsat least a portion of step edge forms a rounded tip and/or varies inthickness along the optical axis. At least a portion of the step edgemay conform to a side of the haptic.

In another aspect of the invention, the step edge has a height H and theoptic edge has a thickness T, and the height H is much less than thethickness T. For example, the height H may be about 0.1 mm, while thethickness T may be in the range of about 0.4 mm or less to about 0.5 mmor more. Alternatively, the height H may be slightly less than, greaterthan, or approximately equal the thickness T.

In yet another aspect of the invention, at least a portion of theperipheral face is disposed at an angle relative to a planeperpendicular to the optical axis that is preferably in the range ofabout 5 degrees to at least about 50 degrees in certain embodiments andin the range of about 15 degrees to about 35 degrees in otherembodiments.

Another aspect of the invention involves a foldable intraocular lensthat comprises an optic body that includes an optical zone and aperipheral zone entirely surrounding the optical zone. The optic bodyhas an anterior face, a substantially opposing posterior face, an opticedge, and an optical axis. The intraocular lens further comprises atleast one haptic integrally formed with the peripheral zone containing adistal posterior face, a proximal posterior face, a step edge disposedat a boundary between the proximal posterior face and the distalposterior face, and a side edge disposed between the optic edge and thestep edge. The proximal posterior face and the posterior face of theoptic body form a continuous surface and the edge corner is formed bythe intersection of the continuous surface with the optic edge, the sideedge, and the step edge. The distal posterior face of the intraocularlens is perpendicular to the optical axis. Preferably, the hapticfurther comprises an anterior face that is also perpendicular to theoptical axis.

Still another aspect of the invention involves a foldable intraocularlens that comprises an optic body that includes an optical zone and aperipheral zone entirely surrounding the optical zone. The optic bodyhas an anterior face, a substantially opposing posterior face, an opticedge, and an optical axis. The anterior face comprises a central face, aperipheral face, and a recessed annular face therebetween disposedposterior to the peripheral face. The intraocular lens further comprisesa cross-sectional profile formed in a plane that passes through theoptical axis. The cross-sectional profile includes the intersection ofthe plane with the recessed annular face and the peripheral face. Thecross-sectional profile is continuous, smooth, and free ofdiscontinuities. The cross-sectional profile may further include theoptic edge. In certain embodiments, the cross-sectional profile consistsof a plurality of arcuate sections. At least a portion of thecross-sectional profile may comprise a line portion disposed at an acuteangle with a line that is parallel to the optical axis.

Yet another aspect of the invention involves a method of making afoldable intraocular lens. The method comprises providing an optic bodyincluding an optical zone and a peripheral zone entirely surrounding theoptical zone, the optic body having an anterior face, a substantiallyopposing posterior face, an optic edge, and an optical axis. Theanterior face comprises a central face, a peripheral face, and arecessed annular face therebetween that is disposed posterior to theperipheral face. The method further comprises integrally forming, at theperipheral zone, at least one haptic comprising a distal posterior face,a proximal posterior face, and a step edge disposed at a boundarytherebetween. The method further comprises forming a side edge disposedbetween the optic edge and the step edge, forming the proximal posteriorface and the posterior face of the optic body into a continuous surface,and forming an edge corner comprising the intersection of the continuoussurface with the optic edge, the side edge, and the step edge.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention may be better understood from thefollowing detailed description when read in conjunction with theaccompanying drawings. Such embodiments, which are for illustrativepurposes only, depict novel and non-obvious aspects of the invention.The drawings include the following five figures, with like numeralsindicating like parts:

FIG. 1 is a perspective view illustrating the anterior surface of anintraocular lens according to one embodiment of the present invention.

FIG. 2 is a perspective view illustrating the posterior surface of theintraocular lens shown in FIG. 1.

FIG. 3 is a side view of a portion of the intraocular lens shown in FIG.1.

FIG. 4 is a perspective view illustrating the posterior surface of anintraocular lens according to another embodiment of the invention.

FIG. 5 is a perspective view illustrating the posterior surface of anintraocular lens according to yet another embodiment of the invention.

FIG. 6 is a perspective view illustrating the posterior surface of anintraocular lens according to still another embodiment of the invention.

FIG. 7 is a cross-sectional view of a portion of the intraocular lensillustrated in FIGS. 1-3.

FIG. 8 is a cross-sectional view of an alternative embodiment of theintraocular lens illustrated in FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

As illustrated in FIGS. 1-3, in certain embodiments, a foldableintraocular lens 10 comprises an optic body 11 including an optical zone12 and a peripheral zone 13 entirely surrounding the optical zone 12.The optic body 11 has an anterior face 14, a substantially opposingposterior face 18, an optic edge 20, and an optical axis 22. Theanterior face 14 comprises a central face 24, a peripheral face 28, anda recessed annular face 30 therebetween that is disposed posterior tothe peripheral face 28. The intraocular lens 10 further comprises atleast one haptic 32 that is integrally formed with the peripheral zone13. The haptic 32 comprises a distal posterior face 34, a proximalposterior face 38, and a step edge 39 disposed at a boundarytherebetween. The haptic further comprises a side edge 40 disposedbetween the optic edge 20 and the step edge 39. The proximal posteriorface 38 and the posterior face 18 of the optic body 11 form a continuoussurface 48. An edge corner 50 is formed by the intersection of thecontinuous surface 48 with the optic edge 20, the side edge 40, and thestep edge 39.

The optic body 11 is preferably generally circular having a radius R_(o)and may be constructed of at least one of the materials commonly usedfor resiliently deformable or foldable optics, such as siliconepolymeric materials, acrylic polymeric materials, hydrogel polymericmaterials, such as polyhydroxyethylmethacrylate, polyphosphazenes,polyurethanes, and mixtures thereof and the like. Alternatively, theoptic body 11 may be constructed of at least one of the commonlyemployed material or materials used for rigid optics, such aspolymethylmethacrylate (PMMA). In a preferred embodiment, the optic body11 is made of SENSAR® brand of acrylic. Other advanced formulations ofsilicone, acrylic, or mixtures thereof are also anticipated. The opticbody 11 material is preferably selected such that the optical zone 12 isoptically clear and exhibits biocompatibility in the environment of theeye. Selection parameters for suitable lens materials are well known tothose of skill in the art. See, for example, David J. Apple, et al.,Intraocular Lenses. Evolution, Design, Complications, and Pathology,(1989) William & Wilkins. Foldable/deformable materials are particularlyadvantageous since optics made from such deformable materials may berolled, folded or otherwise deformed and inserted into the eye through asmall incision. The lens material preferably has a refractive indexallowing a relatively thin, and preferably flexible optic section, forexample, having a center thickness in the range of about 150 microns toabout 1000 microns, depending on the material and the optical power ofthe optic body 11. For example, in one embodiment, the optic body 11 ismade of Sensar® brand of acrylic and an optical power of 20 D. In suchembodiment, the optical zone 12 has a center thickness T_(c) that ispreferably in the range of about 0.5 mm or less to about 1.0 mm or more,more preferably in the range of about 0.7 mm to about 0.9 mm. The centerthickness T_(c) may vary from these ranges depending on factors such asthe lens material and the dioptric power of the optical zone 12. Theoptic body 11 preferably has a diameter of at least about 4 mm to about7 mm or more, more preferably about 5 mm to about 6.5 mm or about 6.0mm. As used herein the term “thickness” generally refers to a dimensionof a portion or feature of the intraocular lens 10 as measuredsubstantially along the optical axis 22.

The intraocular lens 10 may comprise any of the various means availablein the art for centering or otherwise locating the optical zone 12within the eye. For example, as illustrated in FIGS. 1-3, theintraocular lens 10 may comprise one or more fixation members or haptics32. The haptics 32 are preferably integrally made of the same materialas the optic body 11 so as to form a one-piece IOL. Alternatively, thehaptics 32 may be integrally formed in a common mold with the optic body11, but be made of a different material than the optic body 11. In otherinstances, the haptics 32 formed of the same material as the optic body11, but haptics 32 and the optic body 11 materials have differentstates, for instance differing amounts of water content or percentage ofcross-linked polymer. In yet other embodiments, the haptics may beformed separately from the optic body 11 and attached to the optic body11 to provide a three-piece configuration. In such configurations, thehaptics 32 may comprise any of a variety of materials which exhibitsufficient supporting strength and resilience, and which aresubstantially biologically inert in the intended in vivo or in-the-eyeenvironment. Suitable materials for this purpose include, for example,polymeric materials such as polypropylene, PMMA, polycarbonates,polyamides, polyimides, polyacrylates, 2-hydroxymethylmethacrylate, poly(vinylidene fluoride), polytetrafluoroethylene and the like; and metalssuch as stainless steel, platinum, titanium, tantalum, shape-memoryalloys, e.g., nitinol, and the like. In other embodiments, theintraocular lens 10 comprises a positioning means that allows the opticbody 11 to move along the optical axis 22 or be deformed in response todeformation of the capsular bag and/or in response to the ciliarymuscles of the eye.

The optical zone 12 may take any of the forms known in the art. Forexample the optical zone 12 may be biconvex, plano-convex,plano-concave, meniscus, or the like. The optical power of the opticalzone 12 may be either positive or negative. The general profile or shapeof the posterior face 18 and the central face 24 of the optic zone 12may be any used for producing an optic based on refraction of incidentlight. For instance, the posterior face 18, the central face 24, or bothfaces 18, 24 may be spherical with an overall radius of curvature thatis either positive or negative. Alternatively, the profile or shape ofeither the posterior face 18, the central face 24, or both faces 18, 24may be parabolic or any aspheric shape common in the art for reducingaberrations such as spherical aberrations. For example, the posteriorface 18 or the central face 24 may be an aspheric surface designed toreduce spherical aberrations based on either an individual cornea orgroup of corneas as described by Piers et al. in U.S. Pat. No. 6,609,673and U.S. patent application Ser. Nos. 10/119,954, 10/724,852, hereinincorporated by reference. Other aspheric and asymmetric surfaceprofiles of the posterior face 18 or the central face 24 of use withinthe art are also consistent with embodiments of the intraocular lens 10.The posterior face 18 or the central face 24 may alternatively beconfigured to provide more than one focus, for example to correct forboth near and distant vision as described by Portney in U.S. Pat. No.4,898,461.

At least portions of the posterior face 18, the central face 24, or bothfaces 18, 24 of the optical zone 12 may comprise one or more opticalphase plates. In such embodiments, the total optical power of theoptical zone 12 is a combination of the refractive power of theposterior face 18 and the central face 24, and the optical power of theone or more diffraction orders produced by the one or more phase plates.The one or more phase plates may be either a monofocal phase plateproviding one dominant diffraction order or a multifocal phase plate,such as a bifocal phase plate, for providing, for instance, simultaneousnear and distant vision. Other types of phase plates may also be used.For example, the phase plate may be based on a change in the refractiveindex of the material used to form the optical zone 12.

The total optical power of the optical zone 12 is preferably within arange of at least about +2 Diopters to about +50 Diopters or more, morepreferably within a range of about +5 Diopters to about +40 Diopters,and most preferably a range of about +5 Diopters to about +30 Diopters.The total optical power may be either positive or negative, for instancewithin a range of about −15 Diopters or less to about +15 Diopters ormore, or within a range of about −10 Diopters to about +10 Diopters.Other ranges of refractive optical power may be preferred, depending onthe particular application and type of intraocular lens to be used.

In certain embodiments, the haptics 32 are characterized by a hapticthickness T_(h) that is equal to a distance, as measured along theoptical axis 22, between the distal posterior face 34 of the haptic 32and the substantially opposing anterior face 58. Preferably, the hapticthickness T_(h) is greater than or approximately equal to a thicknessT_(o) of the optic edge 20, as measured along the optical axis 22. Thethicknesses T_(h) and T_(o) may be selected based on the particularmaterial from which the intraocular lens 10 is made, the amount ofrigidity desired, the optical power of the lens 10, and other suchfactors. In one embodiment, at least one of the haptic thickness T_(h)and the optic edge thickness T_(o), is preferably in the range of about0.2 mm or less to about 1 mm or more, more preferably in the range ofabout 0.3 mm to about 0.6 mm, and even more preferably in the range ofabout 0.4 mm to about 0.5 mm

The step edge 39 is disposed between the proximal posterior face 38 anddistal posterior face 34 of each haptic 32. The step edge 39 is part ofthe edge corner 50 that forms a continuous boundary around the posteriorface 18 of the optic body 11 to help prevent PCO. In certainembodiments, the step edge 39 has a height H that is preferably in therange of about 0.05 mm or less to about 1 mm or more, more preferably inthe range of about 0.05 mm to about 0.2 mm. In other embodiments, thestep edge 39 has a height H that is in the range of about 0.2 mm toabout 0.5 mm.

As a result of the step edge 39, the distal posterior face 34 of eachhaptics 32 has an anterior offset relative to the proximal posteriorface 38. In certain embodiments, the step edge 39 has a height H that ismuch less than the optic edge thickness T_(o). For example, the height Hmay be about 0.1 mm and the optic edge thickness T_(o) may be in therange of about 0.4 mm or less to about 0.5 mm or more. Alternatively, inother embodiments, the height H is greater than or approximately equalto the optic edge thickness T_(o). The height H may be selected based onvarious design parameters, including, the particular material from whichthe intraocular lens 10 is made, the amount of rigidity desired in thehaptics 32, and other such factors. Preferably, height H is selectedsufficiently large so that the integrity of the contact of the edgecorner 50 with the posterior capsule of the eye is maintained so as tohelp avoid PCO.

In certain embodiments, at least a portion of the step edge 39 is astraight line and is substantially disposed at a radius R₁ from theoptical axis 22. Alternatively or additionally, at least a portion ofthe step edge 39 may be arcuate in shape. The radius R₁ isadvantageously greater than the radius R_(o) of the optic edge 20 sothat a proximal portion of the haptic 32 forms a buttress 51 that ispreferably thicker than a distal portion 52 of the haptic 32 and theedge thickness T_(o). The buttress 51 of each haptic 32 provides greaterhaptic rigidity in the vicinity of the peripheral zone 13, resulting ina biasing force that biases the distal portion 52 of the haptic 32 awayfrom the optical zone 12. The biasing force away from the optical zone12 can favorably act to reduce the tendency of the haptics 32 to stickto the optical zone 12. Such sticking problems have been noted withcertain one-piece IOL materials that are both soft and tacky. Anotherpotential benefit of the step edge 39 is that the thickness of thedistal portion 52 of each haptic 32 T_(h) may be fabricated to be lessthan the thickness of the buttress 51, thus reducing the total volume ofthe intraocular lens 10 and permitting a smaller incision in the eye tobe used during surgery. The greater haptic rigidity in the vicinity ofthe peripheral zone 13 of the optic body 11 also results in a radialforce for centering the intraocular lens 10 within the eye and providesan axial force, as explained below herein. The axial force pushes theedge corner 50 that surrounds the posterior face 18 against theposterior capsule of the eye to help prevent PCO. Disposing the stepedge 39 at a radius R₁ that is greater than R_(o) provides yet anotherpotential advantage. The greater rigidity provided by the buttress 51permits the creation of a flex point W_(f) near the peripheral zone 13that allows the haptic 32 to flex in a plane perpendicular to theoptical axis 22 while maintaining overall rigidity in the vicinity ofW_(f). As illustrated in FIG. 2, the width of the haptic 32 in thevicinity of the flex point W_(f) is less than the haptic thickness inthe vicinity of the flex point W_(f). Thus, the haptic 32 may flex morein a plane perpendicular to the optical axis 22 than in a plane parallelto the optical axis 22.

In certain embodiments, the peripheral zone 13 is substantially formedby the peripheral face 28, the optic edge 20, and the peripheral portionof the posterior face 18. As illustrated in FIG. 1, the peripheral zone13 and the buttress 51 form generally rigid structures, the rigidity ofthe buttress 51 being due, at least in part, to the favorable locationof the step edge 39 at the radius R₁, on the haptic 32. The location ofstep edge 39 at a radius R₁>R_(o) in combination with the rigidity ofthe peripheral zone 13 allows the central face 24 to be recessed suchthat the recessed annular face 30 of the peripheral zone 13 is posteriorto the peripheral face 28. This recessed configuration of the centralface 24, compared to an optic not having the recessed annular face 30,advantageously reduces the total volume of the intraocular lens 10 byreducing the overall thickness of the optical zone 12. Alternatively,the central face 24 is not recessed, thus increasing the overallrigidity of the intraocular lens 10, but also increasing the totalvolume of the lens.

As illustrated in FIG. 3, in certain embodiments, the distal posteriorface 34 of each haptic 32 is perpendicular to the optical axis 22. Inother embodiments, the haptic 32 further comprises an anterior face 58that is also substantially perpendicular to the optical axis. In suchembodiments, the step edge 39 produces an offset relationship betweenthe distal portion 52 of the haptics 32 and the peripheral zone 13. Thisoffset relationship may be favorably used to convert the radial force ofthe ciliary muscles of the eye on the haptics 32 into an axial forcethat biases or pushes the posterior face 18 of the optic body 11 in aposterior direction along the optical axis 22 and against the posteriorcapsule of the eye. This is accomplished without the need for angledhaptics, which can be more difficult and/or expensive to manufacturethan when the distal posterior face 34, the anterior face 58, or boththe distal posterior face 34 and the anterior face 58 are manufacturedsubstantially perpendicular to the optical axis. Alternatively, thehaptics 32 may be manufactured such that the distal posterior face 34and/or the anterior face 58 are disposed at an angle relative to a planeperpendicular to the optical axis 22. This configuration may be used toincrease the amount of posterior bias or force on the posterior face 18of the optic body 11 against the posterior capsule. In suchconfiguration the angle is preferably in the range of about 2 degrees orless to at least about 12 degrees.

In certain embodiments, at least a portion of the peripheral face 28 ofthe optic body 11 is disposed at an angle θ relative to a planeperpendicular to the optical axis. The angle θ is preferably in therange of about 5 degrees or less to at least about 50 degrees, dependingon the dioptric power of the optical zone 12 and the radius of curvatureof the posterior face 18 and the central face 24 of the optical zone 12.In one particular embodiment, the angle θ is preferably in the range ofabout 15 degrees to about 35 degrees, depending upon the dioptric powerof the optical zone 12. The angle θ allows the center thickness of andthe corresponding lens volume to be reduced by an amount suitable forproviding small incision size and insertion force as the intraocularlens moves through the lens inserter.

In certain embodiments, as illustrated in FIG. 4 for example, the stepedge 39 of the haptic 32 tapers radially. The tapered contour of thestep edge 39 serves to elongate the edge corner 50 in the vicinity ofthe haptics 32. Such shapes may be used to better contact integritybetween edge corner 50 and the posterior capsule of the eye, therebyhelping to avoid PCO. Other configurations of the step edge 39 mayalternatively be used to help maintain the integrity of the contact withthe posterior capsule. Referring to FIG. 5, for example, at least aportion of the boundary 44 between the proximal posterior face 38 andthe distal posterior face of the haptic 32 may be disposed at an anglesuch that an opposite side of the step edge conforms to a side of thehaptic 32. In other embodiments, as illustrated in FIG. 6, the height Hof the step edge 39 may vary along the boundary 44 and/or at least aportion of step edge 39 may form a rounded tip. For instance the heightH of the step edge 39 may decrease as the radial distance from theoptical axis 22 increases.

FIG. 7 illustrates a cross-sectional view of a portion of theintraocular lens 10. In certain embodiments, the intraocular lens 10further comprises a cross-sectional profile 60 that is formed by theintersection of a plane passing through the optical axis 22 with therecessed annular face 30 and the peripheral face 28, the cross-sectionalprofile 60 being continuous, smooth, and free of discontinuities. Asused herein, the term “discontinuity” refers to a portion of a profileor surface having a radius of curvature that can scatter light incidentthereon. Such discontinuities may be formed, for example, when twoportions of a cross-sectional profile that are characterized bydifferent slopes intersect one another. The area of intersection isgenerally considered as a discontinuity and the inventors have foundthat such discontinuities, for example as seen in the intraocular lensillustrated in FIG. 3A of U.S. Pat. No. 5,476,513, can contribute toundesired optical effects such as halos or visual poor contrast.

The endpoints of the annular face 30 and the peripheral face 28 alongthe profile 60 may be defined in various ways. For example, theendpoints of the annular face 30 along the profile 60 may be defined asthe points along the profile 60 at which the radius of curvature changesby a certain percentage, for example about 2% or less to about 10% ormore, compared to the radius of curvature at the posterior point 62 ofthe annular face 30. One of the endpoints of the peripheral face 28along the profile 60 may be defined as the point just prior to the pointwhere the surface normal is perpendicular to the optical axis 22 (e.g.,the optic edge 20).

In certain embodiments, as illustrated in FIG. 7, the portion of theprofile 60 that is along the peripheral face 28 forms an acute angle φwith respect to a line 63 that is parallel to the optical axis 22. Theinventors have found that by disposing the peripheral face 28 at theacute angle φ, a reduction in unwanted visual effects can be obtained;for example, a reduction in amount of halos and/or a reduction incontrast sensitivity losses. The reason for this enhanced opticalperformance may be explained as follows. Generally, some of the lightentering the eye is refracted by the peripheral face 28 such that it isdirected towards and is incident upon the optic edge 20. This portion ofrefracted light will be referred to as “edge light.” Some portion ofthis edge light is reflected by the optic edge 20, while the remainderof the edge light is transmitted through the optic edge 20. Any edgelight that is reflected by the optic edge 20 may ultimately be directedtoward or near the fovea, causing one or more of the unwanted visualeffects mentioned above. The amount of edge light reflected by the opticedge 20 depends upon the average incidence angle of the rays containedin the edge light relative to the optic edge 20 surface normal. As theaverage incidence angle of the edge light decreases, the amount of edgelight reflected by the optic edge 20 generally decreases. By disposingthe peripheral face 28 at the acute angle φ, the edge light is refractedby a greater amount by the peripheral face 28 than if the peripheralface 28 were disposed perpendicular or at an obtuse angle with respectto the line 63. Accordingly, the average incidence angle of the edgelight is decreased, meaning that less of the edge light is reflected bythe optic edge 20. Thus, less edge light is directed toward or near thefovea and the overall optical performance is advantageously enhanced.

Referring to FIG. 8, in certain embodiments, the cross-sectional profile60 further comprises the optic edge 20. In such embodiments, theperipheral face 28 smoothly transitions into the optic edge 20 along theprofile 60. Such a smooth transition may be useful to further reduce theamount of unwanted visual effects, as discussed in U.S. Pat. No.6,468,306 to Paul et al., herein incorporated by reference. Thecross-sectional profile 60 preferably consists of a plurality of arcuatesections; however, at least a portion of the cross-sectional profile 60may comprise a line portion 64 disposed at an acute angle with theoptical axis. The line portion 64 preferably forms an acute angle, so asto reduce the amount of light that is internally reflected by the opticedge 20 as discussed above herein.

In certain embodiments, a method of making the foldable intraocular lens10 comprises providing the optic body 11 having the anterior face 14,the substantially opposing posterior face 18, and the optic edge 20. Themethod additionally comprises integrally forming the haptics 32 at theperipheral zone 13 to include the distal posterior face 34, a proximalposterior face 38, and a step edge 39. The method also comprises formingthe side edge 40 between the optic edge 20 and the step edge 39. Themethod further comprises forming the proximal posterior face 38 and theposterior face 18 of the optic body 11 into the continuous surface 48.The method additionally comprises forming the edge corner 50 so that itincludes the intersection of the continuous surface 48 with the opticedge 20, the side edge 40, and the step edge 39.

The intraocular lens 10 is preferably folded or otherwise compressed forinsertion into the capsular bag of an eye via a small incision in thesurface of the eye, for example in the cornea, sclera, or the limbus ofthe eye. Alternatively, the intraocular lens 10 may be placed in frontof the capsular bag or even in the anterior chamber of the eye. Theincision in the eye is preferably less than about 3.5 mm long, morepreferably less than about 3.0 mm long, and even more preferably lessthan about 2.5 mm to about 2.8 mm long.

The intraocular lens 10 is preferably rolled, folded, or otherwiseconfigured for insertion into the eye through the small incision usingforceps, an IOL inserter, or some other suitable device. Once theintraocular lens 10 has been inserted into the eye, the stiffer, moreresilient buttress 51 helps to produce a biasing force on the distalportions 52 of the haptics 32, which helps to prevent the hapticssticking to the optic body 11 and helps center the intraocular lens 10radially and axially.

The intraocular lens may be used alone to replace the natural lens, orto supplement the natural lens or another intraocular lens alreadyinside the eye. The intraocular lens 10 may also be used to provideaccommodation lost due to presbyopia or loss of the natural lens. Insuch uses, the intraocular lens 10 may be either as a solitary lens oruse as part of a lens system. The haptics 34 may also be replaced by orsupplemented with a more complex positioning structure.

The above presents a description of the best mode contemplated ofcarrying out the present invention, and of the manner and process ofmaking and using it, in such full, clear, concise, and exact terms as toenable any person skilled in the art to which it pertains to make anduse this invention. This invention is, however, susceptible tomodifications and alternate constructions from that discussed abovewhich are fully equivalent. Consequently, it is not the intention tolimit this invention to the particular embodiments disclosed. On thecontrary, the intention is to cover modifications and alternateconstructions coming within the spirit and scope of the invention asgenerally expressed by the following claims, which particularly pointout and distinctly claim the subject matter of the invention.

What is claimed is:
 1. A foldable intraocular lens, comprising: an opticbody including an optical zone and a peripheral zone entirelysurrounding the optical zone, the optic body having an anterior face, asubstantially opposing posterior face, an optic edge, and an opticalaxis, the anterior face comprising a central face, a peripheral face,and a recessed annular face therebetween disposed posterior to theperipheral face, the recessed annular face encircling the optical axis;at least one haptic integrally formed with the peripheral zone,comprising: a distal posterior face and a proximal posterior face; and aboundary between the proximal posterior face and the distal posteriorface, the distal posterior face being offset at the boundary from theproximal posterior face in a direction along the optical axis to form astep edge; a side edge disposed between the optic edge and the stepedge; and a continuous surface formed by the proximal posterior face andthe posterior face of the optic body, wherein the recessed annular faceand the at least one haptic each have a thickness and the thickness ofthe recessed annular face is less than the thickness of the at least onehaptic.
 2. The foldable intraocular lens of claim 1, further comprisingan edge corner formed by an intersection of the continuous surface withthe optic edge, the side edge, and the step edge.
 3. The foldableintraocular lens of claim 1, wherein the step edge has a height that isin the range of 0.05 mm to 1 mm.
 4. The foldable intraocular lens ofclaim 1, wherein the haptic is characterized by a haptic thickness equalto a distance along the optical axis between the distal posterior faceand a substantially opposing haptic anterior face.
 5. The foldableintraocular lens of claim 4, wherein the haptic thickness is greaterthan or approximately equal to an optic edge thickness of the optic edgealong the optical axis.
 6. The foldable intraocular lens of claim 4,wherein at least one of the haptic thickness or the optic edge thicknessalong the optical axis is in the range of at about 0.2 mm or less toabout 1 mm or more.
 7. The foldable intraocular lens of claim 1, whereinthe step edge has a height H and the optic edge has a thickness T. 8.The foldable intraocular lens of claim 7, wherein the height H is lessthan the thickness T.
 9. The foldable intraocular lens of claim 7,wherein the thickness T is in the range of about 0.4 mm to about 0.5 mm.10. The foldable intraocular lens of claim 1, wherein at least a portionof the boundary forms a substantially straight line.
 11. The foldableintraocular lens of claim 1, wherein the step tapers radially.